Herrick, Morphology of Nervous System. ^\ 



tra- ventricular lobe, forming a continuous band, as in the 

 lizard. 



The whole lateral and latero-cephalad aspect of the hemi- 

 spheres, on the other hand, is filled, dorsad to the base of the 

 olfactory, with cells of a different type. They have the 

 smaller nuclei and often the pyramidal form and deeper 

 staining of the motor celts. It is true that these distinctions 

 are rather less marked in the frog than in higher verte- 

 brates, but they are perfectly obvious. These cells are also 

 arranged in concentric bands, especially entally 



A very large nidulus of small cells occupies the median 

 portion of each hemisphere dorsad to the anterior commis- 

 sure. It corresponds to the nidulus found in reptiles ventrad 

 to the corpus callosum, but is very large. 



It will not be attempted to homologize the axial lobe 

 and its derivatives with the striatum of mammals, as several 

 considerations seem to forbid a strict comparison. While 

 there can be no doubt that the several divisions of the axial 

 lobe contain the representatives of the striatum, yet there is 

 no such sharp localization of areas nor diflerentiation of 

 function as that seen in mammals. The cells of the central 

 part of the cerebrum seem to be of the most generalized 

 type, and, as I suggested in an earlier paper(') there seems 

 to be good ground for assuming that there are distinct cen- 

 tres of proliferation in these regions. Observations recently 

 made on embryonic brains of rodents seem to indicate that 

 there are such distinct proliferating centres in the cerebrum 

 of mammals from which cortex cells are derived. A closer 

 connection between the so-called Deiter or nutritive cell and 

 neuroblasts than hitherto suspected maybe suggested, as well 

 as the possibility that the so-called basal ganglia are chiefly 

 proliferating and trophic centres. Mr. Turner has arrived 

 at the same conclusion respecting the basal ganglia in birds. 



I "Notes on the Brain of the Alligator," Journal Cincinnati Soc. Nat. Hist., 18 



